1. Field of the Invention
The invention relates to a device for culturing and/or treating cells.
2. Description of the Related Prior Art
DE 42 06 585 C2 describes a device for the mass culture of cells, in particular of hepatocytes on plate-like cell culture carriers, with cells being arranged in a collagen layer on a gas-permeable cell culture carrier. In this connection, the device is constructed like a sandwich, with several cell culture carriers being provided with intercalated collagen layers containing cells. A disadvantage of this device is that the cell chambers are always precisely defined and possess specific volumes. In addition, it is difficult to observe the cells in cell chambers in order to ascertain any possible changes or developmental states.
DE 42 22 345 A1 describes a method for culturing a cell type, in a coculture method using liver cells, with liver cells being cultured on a carrier in a sandwich method. A first matrix layer is arranged between the liver cells and the carrier for anchoring the liver cells, and a second matrix layer is situated over the liver cells.
U.S. Pat. No. 5,449,617 describes a culture vessel in which the culturing is carried out in rigid housings. A disadvantage in this connection is the high proportion of dead volume. In order to supply the cells more efficiently and more uniformly with oxygen, the appliance preferably has to be rotated. This is a continuous stress factor, particularly for cells which are growing in an adherent manner. In this connection, it is not possible to use the so-called sandwich technique to produce hepatocyte cultures over any great length of time since such rotations result in the collagen layers being destroyed. It is only possible to scale up these methods in conjunction with a high dead volume. This limits the scale-up substantially, since an increase in volume also causes the limits of the scale-up to be reached rapidly since new conditions are continually being met with. These are also determined by the fact that the tumbling action achieved by the rotation then increases the pressure and shearing stresses on the cells. On the other hand, if these rotations are not effected, it is no longer possible to ensure that the cells are supplied uniformly with oxygen. This is because of the lateral arrangement of the gas-permeable films/membranes relative to the cell culture space.
U.S. Pat. No. 4,748,124 describes the introduction of defined volumes for the chambers of the culture system. For this purpose, the culture chamber is kept in a compressed state. This suffers from the disadvantage that these chambers have to be fixed in given dimensions (defined) before starting the culturing. This definition of the culture space is regarded as being an advantage. In fact, it is a crucial disadvantage since it makes it impossible to adjust to different culture phases and also makes it impossible for the culture system to increase in size to keep pace with 3-D growth. However, it is only such flexibility which enables the system to be used for developing artificial organs from a small number of starter cultures.
In addition, U.S. Pat. No. 4,748,124 only uses dialysis membranes. This is a considerable disadvantage in the case of primary cells such as hepatocytes, which transport (have to take up and release) products and catabolites, or protein-bound toxins having a substantial, relatively high, molecular weight. Only protein-permeable microporous membranes are able to ensure this.
The present invention is based on the object of providing a device which can be used to react in a very variable manner to the changing conditions, in particular changes in volume (increase and decrease in the volume) when treating and/or culturing cells, where, at the same time an observation should also be possible and, in addition, it should also be made possible to carry out a mass culture.
Because of its simple construction, the novel device is suitable for a mass culture system. In addition, it can be adapted to the particular requirements at the time. Thus, it is possible, beginning with a very small volume and a low number of cells-which are being treated or cultured in the cell chamber or cell compartment, subsequently to increase these parameters to many times the starting volume. This means, for example, that it is possible to start with a small quantity of the material to be investigated and then to allow this material to grow in the cell chamber. This also achieves a saving in costs, particularly in the case of expensive substances.
Because of the possibility of supplying, by way of the stable carrier, air or oxygen which is able to diffuse through the gas-permeable films into the cell chamber, one or more such units can be placed, one above the other in the form of a sandwich, in a conventional incubator. As a result of combining the carrier structure and the oxygenation through the gas-permeable films, there is no need at all for pumping devices for supplying the oxygen and the carbon dioxide, thereby facilitating the operation of the device.
A further advantage is also the fact that, in the novel device, the cell chamber can always be observed in a simple manner.
While cells can be treated or cultured in the lower cell chamber, the upper chamber can be earmarked for supplying nutrient medium, which diffuses into the cell chamber through the microporous film or membrane. For this, the second film has to be appropriately microporous and liquid-permeable. A further advantage of supplying nutrient medium in this way is that the cells in the cell chamber are then subjected to substantially less shearing stress. The cells can be embedded in collagen, both above and below, with nutrient medium then being supplied from above.
Another option for using the second chamber is that this chamber can also be used for producing or xe2x80x9charvestingxe2x80x9d substances which are formed in the cell chamber. Thus, white blood cells, for example, can be cultured in the cell chamber and exposed to an antigen, resulting in the cells beginning to produce antibodies. These antibodies then diffuse through the second film into the second chamber and can then be withdrawn from this chamber. In this way, the cells are retained in the cell chamber. In this case, it is only necessary to ensure that the second film between the cell chamber and the second chamber possesses an appropriate microporosity, such that only the desired substances are able to perfuse through the film.
It is furthermore also advantageous that the medium which is present in the second chamber can be exchanged without disturbing the cells which are present in the cell chamber. Of course, the same also applies in reverse. This results in a system which is capable of being regenerated over a relatively long period of time.
Advantageous further developments and embodiments ensue from the remaining subclaims and from the exemplary embodiment which is described in principle below with the aid of the drawing.